In 1542 Emperor Charles V (February 24, 1500-September 21, 1558) and Viceroy Antonio de Mendoza sent an expedition led by Juan Rodríguez Cabrillo (?-1543) to explore the Pacific Coast of North America. Little is known about Cabrillo, but he most likely was Portuguese.

Cabrillo commanded two ships and was the first European to see San Diego Harbor, the islands of the Santa Barbara Channel, and Monterey Bay. He went as far north as Point Reyes, California, before turning back to winter on San Miguel Island, where he died in early 1543 of injuries suffered in a fall. His pilot, Bartolomé Ferrer, continued the expedition and probably went as far north as the present-day border between California and Oregon.

For the remainder of the 16th century, Spanish ships laden with trade goods from Asia frequently visited the California coast on their way from Manila in the Philippines to Acapulco, Mexico. Growing fears among the Spaniards about the security of California were confirmed when Sir Francis Drake arrived off the Pacific Coast in 1579 and claimed the land for England, naming it New Albion. In 1587 another Englishman, Thomas Cavendish, seized a Spanish ship off the California coast.

The English threat spurred the Spaniards to undertake new explorations. Sebastián Vizcaíno ( 1550?-1615), a prominent Mexico City merchant, sought to explore northward into California. Vizcaíno needed to convince the authorities that he was of sufficiently high standing so that he could raise the money and secure royal permission for an expedition. The first step in doing this was to prove that he and his family were of noble birth. It was important to show that his wife was from a respected family, even though her brother was having trouble with debts.

Consequently, between 1597 and 1600, Vizcaíno offered testimony to prove the noble status of his wife, Magdalena Martínez Orejón, and her brother, Francisco Martínez Orejón. The proofs of nobility were important in defending Vizcaíno's brother-in-law, keeping him out of debtor's prison, and allowing the expedition to proceed. The representative of the king of Spain confirmed Vizcaíno's claims in 1598.

In 1602 Vizcaíno set out to explore both Baja California, and Alta, or northern, California. He mapped most of the California coast and named various features. Many of these names still are valid today. He recommended Monterey Bay as a harbor for Spain’s operations.

Pedro Porter y Casanate (1610-1662) began his career as a sailor in the Spanish navy and rose to the rank of admiral. In 1639 he received permission from the Spanish king to explore the California coast in light ships of his own design.

1. To protect his claim to California, Drake stated that: “…the Spanish neuer had any dealing, or so much as put a foote in this country….”.